Electrical power contact and hinged conductor



Sept. 28, 1965 F. H. COLE 3,309,087

ELECTRICAL POWER CONTACT AND HINGED CONDUCTOR Filed Feb. 10, 1964 2 Sheets-Sheet 1 INVENTOR FRED H. COLE ATTORN EY 5 Sept. 28, 1965 F. H. COLE Filed Feb. 10, 1964 2 Sheets-Sheet 2 3o 36 27 v A FIG. 2

INVENTOR FRED H. COLE BY m ATTORNEYS United States Patent 3,209,087 ELECTRICAL POWER CONTACT AND HINGED CONDUCTOR Fred H. Cole, 1028 5. Sierra Bonita, Los Angeles, Calif. Filed Feb. 10, 1364, Ser. No. 343,535 8 Claims. (Cl. 2008) This invention relates to electrical power contacts and to power disconnect switches comprising a hinged condoctor or switch blade. The invention more particularly involves a novel contact and an arrangement of such contacts for passing large current loads through power switches.

Although many forms of power switch gear have been designed with a hinged construction, and Which W111 withstand heavy service requirements, conventional forms of switch gear employ large castings that required costly machining and special bearings. Therefore, one of the main objects of the present invention is to provide a hinge-type of switch gear that is comparatively light and economical to produce. Another object is to provide a novel form of contact for connecting a tubular switch blade that is hinged between flat surfaces of a bus bar.

In brief, this invention comprises an electrical contact between two conductors, one having a flat surface and the other a curved surface. Contact between such conductors i established by using one or more arcuate conductor fingers, each having first and second raised contacts projecting from concave and convex sides thereof, respectively. The fingers are mounted to and located upon the curved surface conductor as to permit the fingers to be rocked upon the point of contact which the finger makes with the curved surface; and. resilient means is provided for holding the first raised contact of a conductor finger against the curved surface, pressing said contact into surface engagement therewith while tilting the finger and placing the second raised contact into engagement with the fiat surface of a bus bar. The invention further contemplates the use of a pair of bolts for mounting each conductor finger upon the curved surface-of a tubular switch blade and a helical spring disposed coaxial with one of said bolts.

. The electrical contact contemplated by this invention is of particular value in connection with a switch blade that is hinged between the fiat surfaces of a bifurcated bus bar. In particular, a number of conductor fingers of identical construction may be employed and mounted in a balanced fashion to insure that a positive contact will be made between hinged conductors for various positions of movement.

Although the primary object of this invention is to provide an inexpensive construction for a hinged power connector, various other objects of this invention will become apparent in view of the following detailed description and the accompanying drawings.

In the drawings forming a part of this application and in which like parts are identified by like reference numerals throughout the same,

FIG. 1 is a side elevation of a hinged power connector constructed as a preferred embodiment of the present invention; and

FIG. 2 is an enlarged section taken essentially on lines 2-2 of FIG. 1.

Referring to FIG. 1 in particular, there is shown a power switch connector 10 comprising a tubular switch blade 11 mounted from a rotating insulator 12 and pivotally connected to a bifurcated bus bar terminal 13 by a conventional pintle mounting 14. Switch gear 10 further comprises a stationary bus bar 15 secured to a fixed insulator 16 by a bracket 17.

Switch blade 11 is mounted to rotating insulator 12 cially contemplated,

upon a horizontal axis by a pin 18, a mounting yoke 19 and a support plate 20. Adjustable stops 21 and 22 are provided to axially align switch blade 11 between parallel and flat surfaces 23 and 24 of bus bar 15. Three pairs of identical conductor fingers 25 are mounted to the switch-end of switch blade 11 to form an electrical connection between the flat surfaces of bus bar 15, and four pairs of conductor fingers 25 are employed on the opposite end of switch blade 11 to electrically connect with hinged bus bar 13.

This invention more particularly relates to the construction, arrangement and operation of the conductor fingers 25. Referring to FIG. 2, each conductor finger 25 is arcuately formed having a first raised contact 26 and a second raised contact 27, said contacts projecting from the concave and convex sides, respectively, of the fingers. A pair of bolts 28 and 29, provided with retaining nuts 30 and 31, respectively, are used for locating and mounting the arcuate fingers to the switch blade 11. Each bolt is received loosely through the finger and the switch blade, thereby permitting the fingers to be radially moved relative to the switch blade in planes transverse to its longitudinal axis. A coiled helical spring 32 is disposed coaxially relative to each bolt 28 and being located between a pair of washers 33 and 34. Springs 32 bias one end of the conductor finger as to press contact 26 into surface engagement with a curved and prepared contact surface of switch blade 11. Furthermore, the means for mounting fingers 25, using bolts 28 and 29, allow springs 32 to tilt their respective fingers and place the second raised contact of each into surface engagement with the relatively flat and prepared surface of bus bars 13 and 14. A pair of adjustable screws 35 are mounted to the switch blade at points beneath both ends of each finger, and the adjustment of each limits the degree of pivotal movement of fingers 25, respectively.

Each of the contacts 26 and 27 is preferably formed of silver and mounted to fingers 25 in rivet fashion. The fingers themselves, as well as tubular switch blade 11 and bus bars 13 and 15, may be made of copper. It is espe however, that the contact surfaces of both the bus bars and the switch blade may be economically spray-coated with silver to enhance conductivity. Reference numerals 36 and 37 are employed to designate the upper and lower flat contact surfaces of bus bar 13 that have been silver sprayed; and reference numerals 38 and 39, 40 and 41 indicate sprayed areas of contact extending longitudinally of switch blade 11.

This invention further contemplates that each pair of fingers 25 should be mounted to the switch blade in a manner to provide balanced contact with the flat surfaces of each bus bar. For this reason, spring 32 and contact 26 of upper finger 25, as shown in FIG. 2, is located in diametrically opposed fashion to spring 32 and contact 26 of the lower finger 25. This diametric relationship of parts is more particularly indicated by the imaginary reference lines 42 and 43. It will be further noted that contacts 27 are located for engaging surfaces 36 and 37 of the bus bar on a diameter normal to both of the flat surfaces 36 and 37, said diameter being indicated by the reference line 44. The symmetry of this arrangement is of particular value to the construction of a balanced hinged conductor.

The use of four pairs of conductor fingers, two on each side of the pivot axis, is of importance to maximum balance and efficiency of operation. With the arrangement of four pairs of upper and lower contact fingers, adjacent pairs on one side of the pivot axis are located so that their first raised contacts 26 radially engage tubular switch blade 11 on all four surfaces 38, 39, 40 and 41. (Thus, the pair of conductor fingers axially adjacent to those shown in FIG. 2 provide first contacts that engage the switch blade on surfaces 39 and 40, respectively.) All eight second contacts 27 are held against the silversprayed surfaces of the bus bar, four contacts being made with each surface 36 and 37.

It will be apparent that a similar arrangement of conductor fingers may be mounted on the switch-end of switch blade 11. However, since this end is not pivotally connected to bus bar 15, it is unnecessary to provide a balanced contact on both sides of a pivot axis; and a series of three pairs of fingers has been found suitable, although more or fewer contacts may be used depending on load requirements.

Although a preferred form of the invent-ion has been shown and described, it is to be understood that various changes may be made without departing from the spirit of the invention or the scope of the attached claims, and

each of such changes is contemplated.

.arcuate conductor finger having first and second raised contacts projecting from the concave and convex sides thereof, respectively; means for locating .and mounting said arcuate conductor finger to the conductor having a curve-d surface; and resilient means for biasing said conductor finger toward the curved surface to press said first raised contact into surface engagement therewith and tilt said finger to place said second raised contact into surface engagement with the flat surface.

2. The electrical contact of claim 1 wherein said means for locating and mounting said arcuate conductor finger comprises a pair of bolts extending through opposite ends of said finger, respectively, said first and second raised contacts being located intermediate said bolts; and wherein said resilient means for biasing said conductor finger comprises a helical spring disposed coaxial with one of said bolts and held in compression between one end of said bolt and said finger.

3. The electrical contact of claim 2 and further including a pair of stops mounted to said curved surface conductor for limiting the tiltability of said finger between fixed limits.

4. A hinged electrical contact for conducting currents between a cylindrical switch blade having curved surfaces and a bifurcated bus bar having spaced, parallel and relatively flat surfaces; means for pivotally mounting one end of said switch blade upon a pivot axis normal to the flat surfaces of said bus bar; a pair of arcuate conductor fingers, each having first and second raised contacts projecting from the concave and convex sides thereof, re-

spectively; means for locating and mounting said conductor fingers on opposite sides of said switch blade, the first and second contacts of one finger being located on common diameters with the first and second contacts, respectively, of the other finger, said pair of second contacts being located on a line normal to said flat. surfaces; and means for resiliently biasing said conductor fingers toward the switch blade to press each first raised contact into surface engagement therewith and tilt said fingersto place said second raised contacts into surface engagement with the fiat surfaces of said bus bar.

5. The hinged electrical contact of claim 4 and further including a second pair of conductor fingers located adjacent the first recited pair and on the same side of said pivot axis relative to the longitudinal axis of said switch blade; said second pair of conductor fingers being constructed the same as the first recited pair and having first and second raised contacts; means for locating and mounting said second pair of contacts on opposite sides of said switch blade, the first and second contacts of one finger being located on common diameters with the first and second contacts, respectively, of the other finger, and said second contacts being located on a line normal to said flat surfaces; the first contacts of said second pair of fingers being engaged with curved surfaces of said switch blade on a diameter that intersects both the common diameter of the second contacts and the common diameter of the first contacts for the first recited pair of fingers; and means for resiliently biasing said second pair of conductor fingers toward the switch blade to press each first raised contact into surface engagement therewith and tilt said fingers to place said second raised contacts into surface engagement with said flat surfaces of said bus bar.

6. The hinged electrical contact of claim 4 wherein said means for locating and mounting said conductor fingers to said switch blade comprises a pair of mounting bolts for each finger, one bolt extending through opposite ends of respective fingers, the first and second raised contacts of each finger being located intermediate its pair of bolts; and wherein said means for resiliently biasing said conductor fingers comprises a pair of helical springs, one for each finger, disposed coaxial with one bolt of each pair and held in compression between one end of said one bolt and the respective fingers, said springs and mounting bolts being located on diametrically opposite sides of said switch blade.

7. The hinged electrical contact of claim 4 and further including three additional pairs of conductor fingers, one pair being located adjacent the first recited pair of fingers and on the same side of said pivot axis and two pairs of conductor fingers being located adjacent each other on the opposite side of said pivot axis; each of said additional pairs of fingers being constructed the same as the first recited pair and having first and second raised contacts;

means for located and mounting each pair of fingers on opposite sides of said switch blade, the first and second contacts of one finger of each pair being located on common diameters with the first and second contacts, respectively, of the other finger of its pair, and each pair of second contacts being located on a line normal to said fiat surfaces; and means for resiliently biasing said conductor fingers toward the curved surface of said switch blade to press each first raised contact into surface engagement therewith and tilt said fingers to place said second raised contacts into surface engagement with the fiat surfaces of said bus bar.

8. The hinged electrical contact of claim 7 wherein said cylindrical switch blade has four curved surfaces of contact arranged in upper and lower pairs on opposite sides of said pivot axis; the first contacts of the first recited fingers being engaged with one of said upper and one of said lower surfaces, respectively; and the first contacts of the adjacent one pair of additional fingers being engaged with the other of said upper and lower surfaces, respectively; the first contacts of one of said two pairs of adjacent fingers being engaged, respectively, with the upper and lower surfaces engaged by the contacts of the first recited fingers and the first contacts of the other pair being engaged with the other upper and lower surfaces, respectively.

No references cited.

KATHLEEN H. CLAFFY, Primary Examiner. 

1. AN ELECTRICAL CONTAC BETWEEN TWO CONDUCTORS, ONE HAVING A FLAT SURFACE AND THE OTHER A CURVED SURFACE; AN ARCUATE CONDUCTOR FINGER HAVING FIRST AND SECOND RAISED CONTACTS PROJECTING FROM THE CONCAVE AND CONVEX SIDES THEREOF, RESPECTIVELY; MEANS FOR LOCATING AND MOUNTING SAID ARCUATE CONDUCTOR FINGER TO THE CONDUCTOR HAVING A CURVED SURFACE; AND RESILIENT MEANS FOR BIASING SAID CONDUCTOR FINGER TOWARD THE CURVED SURFACE TO PRESS SAID FIRST RAISED CONTACT INTO SURFACE ENGAGEMENT THEREWITH AND TILT SAID FINGER TO PLACE SAID SECOND RAISED CONTACT INTO SURFACE ENGAGEMENT WITH THE FLAT SURFACE. 